Green tea and diabetes type 2

The fountain of youth still remains elusive, but there's something that seems close: green tea. People have been drinking tea for centuries, and today it's the second most popular drink in the world (after water). Some of that popularity may stem from the many widely recognized benefits of tea, including its reported power to prevent cancer and to sharpen mental health. But tea may offer health benefits related to diabetes, too.

“We know people with diabetes have problems metabolizing sugar, ” says Suzanne Steinbaum, DO, a cardiologist, director of women’s heart health at Lenox Hill Hospital in New York City. “Insulin comes along to decrease sugar, but with type 2 diabetes, the body isn’t so sensitive to insulin, so blood sugar levels go up. Through a complex biochemical reaction, tea — especially green tea — helps sensitize cells so they are better able to metabolize sugar. Green tea is good for people with diabetes because it helps the metabolic system function better.”

A 2013 research review published in the Diabetes and Metabolism Journal outlined the potential benefits of tea when it comes to diabetes as well as obesity, which is a risk factor for diabetes. It highlighted a Japanese study that found that people who drank 6 or more cups of green tea a day were 33 percent less likely to develop type 2 diabetes than were people who drank less than a cup of green tea a week. It also reported on Taiwanese research that found that people who drank green tea regularly for more than a decade had smaller waists and a lower body fat composition than those who weren't regular consumers of green tea.

Drinking tea for diabetes is such a good idea because tea contains substances called polyphenols, which are antioxidants found in every plant. “Polyphenols help reduce oxidative stress and cause vasodilation (widening of the arteries), which decreases blood pressure, prevents clotting, and reduces cholesterol, ” Dr. Steinbaum says. All of these activities reduce the risk for heart disease, which is elevated in people with diabetes. Polyphenols in green tea can also help regulate glucose in the body, helping to prevent or control diabetes.

Drinking Tea for Diabetes: Green Tea or Black Tea?

When it comes to drinking tea for diabetes, Steinbaum says benefits are tied to all teas, but that green tea is the clear winner. "For one, when you drink green tea for diabetes, you will get a higher level of polyphenols than you would get in black, ” she explains. It’s the polyphenols in fruits and vegetables that give them their bright colors. So, having more color means that green tea is richer in polyphenols. “Of the black teas, the more orange the color, the higher the polyphenols, ” she adds.

"Green tea is good for people with diabetes because it helps the metabolic system function better." Suzanne Steinbaum, DO

Besides its color, green tea also contains higher polyphenol levels because it's prepared from unfermented leaves, "so it is really pure, ” Steinbaum says. Black tea, on the other hand, is made from leaves that are fully fermented, which robs it of some nutrients. “Plus, some black tea varieties can have two to three times more caffeine than green, which isn’t good in excess, ” she says.

Polyphenols: Beyond Drinking Tea for Diabetes

The benefits of tea are clear. But besides tea, a number of foods high in polyphenols also can help prevent and manage type 2 diabetes. “The fruits highest in polyphenols are berries, grapes, apples, and pomegranates — because of their rich color, ” Steinbaum says. Broccoli, onions, garlic, tomatoes, eggplant, and spinach are also good sources, as are cranberries, blood oranges, blackberries, blueberries, raspberries, strawberries, rhubarb, lemons, limes, and kiwis. “We know red wine contains resveratrol, which is a polyphenol — the highest concentration is in Bordeaux, ” Steinbaum says.

Cocoa is also a good source — a reason to eat a piece of dark chocolate now and then. “And for those following a vegetarian diet, there are also a number of foods high in polyphenols that also provide protein, such as red beans, black beans, pinto beans, pistachios, walnuts, chickpeas, and all the nut butters, ” she says.

Overall, in addition to drinking tea for diabetes, eating a diet that’s good for your blood sugar isn’t complicated. “Type 2 diabetes tends to be driven by dietary lifestyle choices, " Steinbaum says. "When we talk about prevention, having a diet filled with polyphenols will help the body better metabolize sugar." Hands down, eating foods rich in polyphenols — such as garlic and brightly colored fruits and vegetables — and drinking tea for diabetes, especially green tea, are great ideas for anyone trying to manage or prevent diabetes.